A far-right contender to become Austria's head of state was forced to denounce the Nazis today, promising to uphold a national ban on denying the Holocaust after previously insisting that it was a matter of free speech.

Amid growing uproar over a tabloid campaign to make her president, Barbara Rosenkranz, a deputy leader of the far-right Freedom party, surprised the Austrian elite last week by announcing she would challenge the incumbent, Heinz Fischer, for the Austrian presidency next month.

Rosenkranz, a mother of 10 married to a man who was prominent on the Austrian neo-Nazi scene for two decades, has repeatedly criticised Austria's laws criminalising denial of the Holocaust. Asked on national radio last week whether she believed the Nazis murdered millions of Jews in concentration camp gas chambers, she answered evasively, adding that freedom of expression also meant allowing "absurd, bizarre opinions".

Following an outcry and criticism from her main backer, the mass-circulation Kronen Zeitung newspaper, she publicly signed a statement today pledging never to contest the country's anti-Nazi legislation.

"Democracy, freedom and human dignity have always been the foundations of my views and my political activities. This is why I condemn the crimes of the era of the National Socialistic regime. I distinctively dissociate myself from Nazi ideology," she said in the statement, according to the Austrian Times.

The about-face was dismissed as meaningless by her political opponents, and an opinion poll showed that two out of five Austrians believed she was damaging the country with her views.

Rosenkranz is the sole challenger running against Fischer, a Social Democrat, with the mainstream Christian democrats, or Austrian People's Party, failing to put up a contender.

While she has little chance of winning, her campaign is seen as a test by the extreme right and its powerful backers to gauge how much support they can muster. They hope she will be helped by the absence of a mainstream centre-right candidate.

Rosenkranz is running a campaign strong on xenophobia and opposition to the European Union, opposing immigration and calling for the closure of Austria's borders with the newer EU countries of central Europe.

The Kronen Zeitung and its elderly publisher, Hans Dichand, are very powerful in Austria. Last week Dichand endorsed the Rosenkranz candidacy, writing that she was "a courageous mother" who would make a "good Austrian president". He added that her main pitch would be to blame the EU for "the completely incomprehensible opening of the borders to the east".

Vienna's Jewish community said it was unacceptable for "other political posts in the country to be occupied by cellar Nazis" and described her candidacy as "contempt for the 65,000 Austrian Jews murdered in the Shoah".

The far-right Freedom party leader, Heinz-Christian Strache, said Rosenkranz might win 35% of the vote next month.